In recent years, application of liquid crystal displays (LCD) has been growing, including not only notebook personal computers and monitors but also television sets (TV).
As a light diffuser plate (1 mm to 3 mm thick) for a direct-underlying-type backlight mounted on TV where high brightness is particularly requested, when the screen size is around 20 inches, a light diffuser plate of acrylic resin is mainly used. However, acrylic resins have poor dimensional stability because of their poor heat resistance and high hygroscopicity, so that light diffuser plates of large screen size have a problem of warp-deformation.
Therefore, nowadays polycarbonate resins, which are more excellent in heat resistance and hygroscopicity than acrylic resins, are used as matrix resins for light diffuser plates. The demand of polycarbonate resins is growing.
Compositions obtained by blending light-diff-using agents with ordinary polycarbonate resins are already publicly known (see, for example, Patent documents 1 to 5).
A light diffuser plate comprising a polycarbonate resin as a transparent resin for matrix is more excellent in heat resistance, impact strength, and hygroscopicity than a light diffuser plate of acrylic resin. When a light-diffusing agent is blended with a polycarbonate resin, however, the diffusing-light obtained after light diffusion exhibits yellowish color tone and lowered brightness because of poor transparency of the polycarbonate resin itself as compared with an acrylic resin. This point has been a disadvantage of light diffuser plate of polycarbonate resin.
That is, light diff-user plates of polycarbonate resin have a disadvantage that they absorb more light at the side of short wavelength than light diffuser plates of acrylic resin during repeated scattering (multiple scattering), shifting the diffusing-light to the longer wavelength. Accordingly, light diffuser plates of polycarbonate resin cause large deterioration in brightness and color tone on the resulting diffusing-light, and improvement of their light guiding properties is desired.    Patent document 1: Description of Japanese Patent No. 3100853    Patent document 2: Description of Japanese Patent No. 3357809    Patent document 3: Description of Japanese Patent No. 3447156    Patent document 4: Description of Japanese Patent No. 3447848    Patent document 5: Japanese Patent Laid-open Publication No. H10-46018